DESCRIPTION: The aims of the project are twofold: 1. To determine whether an improved portable X-Ray Fluorescence (XRF) analyzer will give results of lead in air determinations of sufficient accuracy to support its use in compliance measurements for determination of a workers exposure in comparison to the OSHA Permissible Exposure Limit (PEL), or other limit value such as the Threshold Limit Value (TLV). 2. To determine which inhalable sampler is most appropriate for use with on-site XRF analysis in evaluating workers exposure to inorganic lead dust in accordance with a possible change in the TLV to involve sampling the inhalable fraction of dust. The TLV Committee of the American Conference of Governmental Industrial Hygienists has indicated that all current "total" dust exposure standards are to be evaluated in order to re-state them in terms of size-selective criteria appropriate to health effects. In the case of dust containing inorganic lead the likely outcome is a change to a standard based on the inhalable fraction. A large-scale field comparison between samplers for both standards is recommended when a significant increase or decrease (> 30 percent) is expected in the measured dust levels as a result of the change. The use of an on-site analyzer could reduce the costs of this survey by as much as 50 percent. The study will involve the collection of samples using the standard closed-face cassette for "total" dust and the following inhalable samplers: The Button sampler (U. of Cincinnati), the lOM (Institute of Occupational Medicine) sampler, and the CIS or GSP sampler (BIA, Germany). The collected samples will be analyzed by pre- and post-sampling weighing of the filters, on-filter analysis of the lead content using a field-portable XRF device, and confirmation analysis in the laboratory by wet chemical digestion and atomic absorption spectrophotometry. If a particular inhalable sampler is found to give results that are sufficiently accurate and precise when used with the portable XRF unit, it will be incorporated in a larger project to gather data to assess the effects of any proposed TLV change.